The present invention relates to cryostat construction and in particular relates to a low-heat transfer stiff suspension system for supporting a cold inner vessel from a warmer surrounding outer vessel. Aspects of the present invention include the provision of a suspension system for use in the construction of nuclear magnetic resonance (NMR) imaging systems and other systems which contain superconducting coils. The suspension system must allow for substantial thermal contraction and expansion, be capable of withstanding forces experienced in operation and in transportation and minimize heat transfer into the cryostat.
Conventional cryostats for these uses commonly "hang" the cold inner vessel from the outer vessel with long thin elements of low thermal conductivity. Many of these designs require disruption of the cryostat vacuum for the purpose of inserting temporary stiffening supports to protect the magnet and internal components during transportation. Other designs attempt to avoid such disruption by providing low thermal conductive pins which the inner vessel contacts during transportation. Avoiding disruption of the cryostat vacuum is very important since the process of drawing the vacuum and the cool down of an NMR magnet assembly can take approximately one week and require the use of cryogens costing over $10,000.